“It’s a birth control method, the equivalent of family planning for humans,” said Kostas Bourtzis, a molecular biologist with the IAEA’s insect pest control laboratory.

Brazil is scrambling to eradicate the Aedes mosquito that has caused an epidemic of dengue and more recently an outbreak of Zika, a virus associated with an alarming surge in cases of babies born with abnormally small heads.

The new epidemic threatens to scare visitors away from the Rio 2016 Olympic Games in August. A Brazilian non-profit organisation called Moscamed will breed up to 12 million male mosquitoes a week and then sterilise them with the cobalt-60 irradiator, produced by Canadian company MDS Nordion, said Dr Bourtzis.

The sterile males will be released into target areas to mate with wild females who will lay eggs that produce no offspring, he said during an IAEA meeting of mosquito control experts.

After an initial programme in a dozen towns near Juazeiro, the Brazilian government would have to decide on scaling up the sterile mosquito production with more funding for use in cities, where they would be released from the air, possibly from drones, said Dr Bourtzis.

With no cure or vaccine available for Zika, which has spread to more than 30 countries, mostly in the Americas, the only way to contain the virus is to reduce the mosquito population.

Brazilian researchers are also experimenting with radiation. The Fiocruz biomedical research institute has released 30,000 sterile mosquitoes on an island 217 miles off the coast of northeast Brazil.

Much remains unknown about Zika, including whether the virus actually causes microcephaly. Brazil said it has confirmed more than 500 cases, and considers most of them to be related to Zika infections in the mothers. Brazil is investigating more than 3,900 additional suspected cases of microcephaly.